1. Field of the Invention
The present invention relates to a laser machining apparatus for performing laser machining of welding, cutting, etc. by applying laser beams on a workpiece from machining tools, which is suitable for use in a motor vehicle manufacturing line.
2. Description of the Related Art
Recently, the laser welding using a YAG laser as an optical energy supply source has increasingly been adopted especially on a motor vehicle manufacturing line. The reason for this is that the laser welding has an advantage of achieving high rigidity and lightweight easily in terms of vehicle body design over the spot welding.
Regarding the positioning of a machining tool that applies a laser beam on a workpiece, the use of a special positioning device and a robot capable of programing a travel path has already been proposed. Also, an example in which a line configuration such that a plurality of laser generators are prepared, and laser beams are supplied to a plurality of locations where welding is performed employing an optical distribution system is considered (Japanese Patent Laid-Open Publication No. 4-238689) has been reported.
However, in the case where the system is used in the manufacturing line of the motor vehicles, the laser machining apparatus in which networks of the fiber-optic cables is simplified for effectively supplying a laser output to the manufacturing line is not yet provided.
A primary object of the present invention is to provide a laser machining apparatus capable of providing laser beams in a manufacturing line of the motor vehicles by simplifying a network of fiber-optic cables.
The laser machining apparatus of the present invention comprises: a plurality of laser generators; a plurality machining tools for focusing laser beams; machining tool moving means for respectively moving the machining tools along predetermined paths; fiber-optic cables forming optical transmission paths for guiding the laser beams outputted from the laser generators to the machining tools; laser beam confluence means intervened in the optical transmission paths to join at least part of laser beams outputted from the laser generators to be confluent into a fiber-optic cable or fiber-optic cables of the number smaller than that of the laser generators; and laser beam distribution means intervened in the optical transmission paths to distribute the confluent laser beam to a plurality of laser beam outlets. The laser beam distributed to the laser beam outlet is focused at the machining tool for performing machining.
The laser generators may be divided into a plurality of groups, and at least part of the laser beams outputted from the laser generators in each group are joined to be confluent into a fiber-optic cable or fiber-optic cables of the number smaller than that of the laser generators in the group by the laser beam confluence means and the confluent laser beam in each group is distributed to the plurality of laser beam outlets by the laser beam distribution means.
The laser beam confluent means may be constituted using a laser beam superposing optical element for joining the laser beams utilizing at least one of a difference of polarizing directions and a difference of wavelengths of the laser beams.
It is preferable that the output levels of the respective laser generators are adjustable in accordance with the sum of laser beam outputs required by the respective machining tools. Further, it is preferable that a speed of the laser machining is varied in accordance with the laser beam outputs distributed to the laser beam outlets by the machining tool moving means.